1. Field of the Invention
The present invention relates to a camera having a zoom lens system as a taking lens, and more specifically relates to a camera which controls a zooming or focusing operation of the taking lens in response to conditions of a photographing scene (i.e., a subject distance, a kind of a light source and so on) or a defocus amount of the taking lens respectively.
2. Description of the Prior Art
Conventionally, for example, in the case where a photographer wants to carry out zoom-photographing of a subject using a camera equipped with a zoom lens system, the photographing operation has been performed after a magnification is determined as he chooses by a photographer's manual zooming operation in such a manner as to operate a WIDE/TELE zooming driving button or a zoom ring. Therefore, a relatively long time has been required for the photographer's determination of the magnification. For this reason, a zoom photographing system called an automatic program zooming function has been proposed which automatically determines the magnification in response to the subject distance and automatically controls a focal length so that the determined magnification can be obtained.
However, according to the conventional automatic program zooming function, the relation between the subject distance and the magnification is determined in advance by only one program diagram thereof, which gives a photographer a disadvantage when for example, a baby is photographed in the whole image plane at a relatively short distance indoors, or a subject such as the whole body of a child on a ground is photographed in the whole image plane at a relatively long distance outdoors.
Further, according to the above-described automatic program zooming function, it is designed that the zooming lens is capable of being driven in the whole zooming range at both the times of indoor photographing in which the zooming lens is frequently driven nearby the shortest focal length condition, and outdoor photographing in which it is frequently driven nearby the longest focal length condition. Accordingly, there is a drawback that unnecessary judgment, control and actions in accordance with whether the present photographing situation is indoor photographing or outdoor photographing are required to be performed.
Furthermore, in such conventional automatic program zooming function, the zoom control is performed even when the taking lens is in extreme out-of-focus state. Therefore, for example, in the case where the zoom lens system having a focusing function of an inner-focus type or a rear-focus type is adopted as the taking lens, it is made impossible to control the zooming operation with accuracy because the degree of the out-of-focus condition becomes higher, causing the zooming lens consisting of a variator and a compensator, for example, to be excessively driven or to be made unsteady.
On the other hand, a conventional camera having the following zoom lens system as the taking lens has been known: the zooming lens performs the zooming operation in the normal photographing distance range, while it is driven into the macro range by a motor in order to perform the focusing operation when the subject is positioned at a shorter distance than the shortest photographing distance in the normal photographing distance range.
According to the camera having such conventional constitution, when the position of the subject is shifted from the macro range to the normal photographing distance range, the focusing operation by the zooming lens is shifted to that of a normal focusing lens. That is, when the zooming lens reaches the zooming range from the macro range, the normal focusing lens performs the focusing operation in place of the zooming lens. However, at this time, it has been brought into question how the zooming operation by the zooming lens in the zooming range should be controlled, that is, how the focal length of the taking lens should be set.
Meanwhile, a conventional camera has been proposed on which velocity setting means is provided so that a photographer can set the drive velocity of the zooming lens in the zooming operation as he chooses.
However, the conventional camera thus constituted has produced a disadvantage in the case of the macro focusing operation by the zooming lens in that focusing accuracy is deteriorated if the drive velocity of the zooming lens is set high at zoom photographing by the velocity setting means. This is because accurate focusing operation is made difficult due to the high velocity, and especially in a power focusing mode, stable focusing operation becomes impossible to be performed.
Also in the case of a video camera, if the drive velocity of the zooming lens is set high by the velocity setting means, an angle of view is rapidly changed due to the high drive velocity, resulting in a reproduced picture image hard to be seen clearly.